1. Field of the Invention
This invention relates to composite electronic parts such as a filter, a timing extraction circuit, or a differentiating circuit.
2. Description of the Prior Art
As to filters, the structures shown in FIGS. 5 and 6 are conventionally known. In the structure shown in FIG. 5, an open-stub 32 and a short-stub 33 are formed on a dielectric substrate 31 on the under-surface of which an earth electrode is formed. The open-stub 32, short-stub 33 and the like are pattern-formed by, e.g., printing. One end of the short-stub 33 is connected to the earth electrode via a through-hole 37. Further, on the dielectric substrate 31, chip resistors 35, 36 are carried. And wiring 34 is pattern-formed so that it connects these chip resistors 35, 36, open-stub 32 and short-stub 33. The wiring 34 and the chip resistors 35, 36 are electrically connected by, e.g., soldering.
Still further, in the structure shown in FIG. 6, chip-type delay lines 43, 44 and chip resistors 45, 46 are carried on a dielectric substrate 41 on which wiring 42 is formed with a predetermined pattern, and these chip parts and the wiring 42 are electrically connected by, e.g., soldering.
However, the conventional filters mentioned above have problems as follows. That is, the former has a hood high-frequency characteristic because of using the open-stub 32 and the short-stub 33 which are pattern-formed, but the former requires a wide substrate area for pattern-forming of these stubs, thereby resulting in a large size. Furthermore, a filter like this has a disadvantage of being unable to adjust the frequency characteristic.
The latter uses the chip-type delay lines 43, 44 instead of the open-stub and short-stub, and thus requires only a smaller substrate area than that of the former, and further is able to adjust frequency by replacing the delay lines 43, 44 with other chips, but has the disadvantages of a worse high-frequency characteristic than that of the former and an increase in the number of parts.